Dipstick assembly

ABSTRACT

An oil level dipstick assembly provides a check valve that effects an air seal when the dipstick is removed, but which valve is open when the dipstick is in place to permit the stick to reliably measure the oil level in an oil reservoir for an apparatus having moving parts therein, even when the apparatus is in operation.

[ May 16, 1972 United States Patent Sasgen ...33/126.7 Rains.......................................74/606 n 0 S n 8 I a C 90 56 99 U9 1 29 33 73 15 22 m k m P t S e m YF L Be M 8 E s S Am K w Tm Sm PB Iv BM .1] 42 57 [rt [73 1 Assigneez Power parts Company FOREIGN PATENTS OR APPLICATIONS 22 Filed: Sept. 2, 1970 882,632 8/1933 Australia Primary ExaminerRobert B. Hull Att0rneyLettvin and Gerstman App]. No.:

33/126 7 ABSTRACT ..G01123/04 33 2 7 R An oil level dipstick assembly provides a check valve that effects an air seal when the dipstick is removed, but which valve [51] Int.

References m is open when the dipstick is in place to permit the stick to reliably measure the oil level in an oil reservoir for an apparatus having moving parts therein, even when the apparatus is in operation.

UN lTED STATES PATENTS 1,717,188 Ciomei 1,988,181

Spaeth.................................33/126.7 4 Claims, 3 Drawing Figures FIELD OF THE INVENTION This invention relates to an oil level dipstick, and more particularly, to a dipstick assembly for enabling reading of the oil level in the oil reservoir of reciprocating apparatus, such as an internal combustion engine or air compressor without terminating operation of the apparatus.

BACKGROUND OF THE INVENTION Conventional oil level dipsticks, which comprise a marked blade for insertion into a crankcase, or into the oil reservoir of an air compressor or other machine with reciprocating parts, to measure oil level cannot normally be removed and accurately read unless operation of the reciprocating apparatus is terminated. The withdrawal of a conventional dipstick during operation of the apparatus opens the crankcase to the atmosphere, thereby upsetting the gas-pressure conditions within the reciprocating apparatus. The amount of air which may be drawn in through a dipstick opening and discharged through such opening is sufficient to discharge oil to atmosphere in the discharge cycle and to draw in unfiltered air in the suction cycle, resulting in either undesirable oil loss or contamination of the oil in the crankcase or reservoir. At-

tempts at shielding the conventional measuring blade prior hereto has been ineffective to prevent oil splash because the reservoir is subject to oil volume changes depending upon the position of the reciprocating apparatus.

The aforementioned problems associated with conventional oil level dipsticks are obviated by the present invention, in which a dipstick assembly comprising a sleeve-shield, a normally closed check valve, and a dipstick for engaging and opening the valve are provided so as to maintain the crankcase or reservoir essentially sealed from the ambient atmosphere when the stick is removed for a reading, and wherein effective shielding of the stick from oil splash within the apparatus is effected.

BRIEF DESCRIPTION OF THE INVENTION In accordance with the present invention, there is provided an oil level dipstick assembly including a typical elongated measuring rod the lower portion of which is adapted for communication with the oil level in the reservoir and which bears indicia for enabling an operator to ascertain the oil level. The improvement comprises a housing for the dipstick that includes an elongated tube or sleeve for receiving therein the dipstick and a movable housing carried at the lower end of the tube maintaining a valve in position to be opened when the dipstick is in stored position in the sleeve and which automatically closes the valve when the dipstick is removed for readmg.

The valve is a simple one that includes a ball positioned to normally close the tubes lower opening, thereby providing a seal against leakage to atmosphere when the elongated rod is not in place within the tube. The valve ball is positioned for downward movement with the housing against a spring bias, thereby opening the interior of the sleeve to entry of oil for purpose of measurement by the dipstick.

A more detailed explanation of the invention is provided in the following description and claims, and is illustrated in the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an elevational view, with portions partially broken away and with other portions taken in section along the longitudinal axis, showing an oil level dipstick assembly constructed in accord with the present invention;

FIG. 2 is a view taken looking from the right of FIG. 1 and showing the assembly with the dipstick removed and with portions broken away and with other portions in cross-sectional view; and

FIG. 3 is an elevational view of the dipstick of FIG. 1 but taken looking from the right in relation to FIG. 1.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENT Referring now to the drawings, the oil dipstick assembly, generally indicated at 10, includes an elongated simple tube or sleeve 12, of uniform internal diameter, that is rigidly secured by welding W or the like to the wall of a housing H that has an aperture for the sleeve to pass through. The welding not only serves to rigidly position the sleeve 12 but serves to effect a gas tight seal between wall W and sleeve 12. It will be understood that the housing H is shown illustratively and as a fragment since it does not comprise part of the invention herein described.

The elongated sleeve 12 has its ends disposed on opposite sides of the housing H so that the lower or measuring end is positioned to enter the oil within the housing, while the upper or access end presents a mounting for the dipstick. The upper access end of sleeve 12 is internally threaded at 14. The lower measuring end of sleeve 12 is provided with a spherically ground valve seal 16 at its terminus adapted to be sealingly engaged by a valve ball. The outer periphery of sleeve 12 adjacent seat 16 is grooved to receive a snap ring 18 that serves as an abutment. The wall of sleeve 12 is provided with a bleed bore 20 that opens to the interior of the housing H and prevents undesirable rise of oil in sleeve 12 above the level of bore 20.

An elongated dipstick generally at 22, includes a head 24 and a rod-like member 26 secured to head 24. The head has a threaded shank portion 28 for cooperation with sleeve threads 14, a depending reduced shank 30 for close but non-contacting fit into sleeve 12, and an enlarged head 32. A groove 34 between head 32 and threads 28 carries an O-ring 36 positioned and dimensioned for sealing compression between head 32 and the upper edge of sleeve 12. The head 32 is provided with outwardly extending turnpins 38 for developing the forces necessary to manipulate dipstick 22 during screwing and unscrewing relative to sleeve 12. The shank 30 is tapped to provide a screw connection between head 24 and rod-like member 26.

The rod-like member 26 is of smaller cross section dimension that shank 30 so as to clear the inner wall of sleeve 12. The lower end of rod 26 is provided with an axially elongated flat 40 that has indicia marked thereon, as seen in FIG. 1, for purposes of retaining oil thereon and indicating the level of oil being measured. At a point spaced closely above the upper end of flat 40, the rod 26 is grooved to receive an O-ring 42 or other flange like member for restricting movement of oil upwardly in the annular space between sleeve 12 and rod 28, and serving to prevent oil smear by contact of the dipstick with the inner wall of sleeve 12. The length of dipstick 22 is carefully selected so that the lowermost end of stick 22 will engage and unseat a ball valve 44 as seen in FIG. 1.

The ball valve 44 is of a size and shape to seat against valve seat 16, as in FIG. 2, to both prevent oil passing outwardly past valve 44 and through sleeve 12, and to prevent entry of air through sleeve 12 and past valve 44.

A retainer means is provided for holding the valve 44 in proper position for movement between the positions of FIGS. 1 and 2 and for normally biasing valve 44 to its closed position of FIG. 2. The retainer means includes tube-like member 46 that surrounds the lower end of sleeve 12 leaving an annular space therebetween. The tube-like member 46 is internally grooved adjacent each end to receive snap-ring retainers 48 and 50 which respectively engage washer like discs 49 and 51 which slidably enter tube-like member 46. A coil compression spring 52 surrounding sleeve 12 and abutting rings 18 and 49 serves to bias member 46 upwardly relative to sleeve 12. The disc 51 has a smaller center aperture 51a adapted to receive and center the ball valve 44, thereby preventing dislodgement from centered relation with valve seat 16 when the valve 44 is unseated as in FIG. 1. The lower end of tube-like member 46 between discs 49 and 51, but closer to disc 51, is transversely apertured at 54 to provide for entry of oil (as indicated by arrows) from the reservoir to the interior of sleeve 12 when valve 44 is unseated, so that the oil will reach its level in sleeve 12.

The operation of the construction will be readily understood from the foregoing description. As dipstick 22 is unscrewed, preparatory to removal, the bias of spring 52 moves valve 44 to the seating position of FIG. 2. As dipstick 22 is screwed to its innermost position, its lower end engages and unseats valve 44 permitting the oil level to be measured. The axial length of the screw-threads on sleeve 12 at 14 and on shank 28 is selected to substantially prevent leakage in the transition period for valve 44 as it moves between fully open and fully closed positions, with the valve 44 fully seating before the threads are fully disengaged. Such length of threaded portions also serves to maintain the dipstick centered in sleeve 12 without the lower tip of stick 22 touching the wall of sleeve 12. The shank 30 in close position to the wall of tube 12 also cooperates in centering the dipstick.

The construction disclosed is extremely simple and inexpensive but very effective in providing a true measure of the oil level. Surging of oil within the housing has substantially no effect on the measurement and the anti-smear collar on the stick prevents false readings. The use of snap-rings and washer-like parts permits of simple assembly and use of inexpensively produced parts.

Although an illustrative embodiment of the invention has been shown and described, it is to be understood that various modifications and substitutions may be made by those skilled in the art without departing from the spirit and scope of the present invention.

What is claimed is:

1. In an oil level dipstick assembly that includes an elongated measuring rod the lower portion of which is adapted for communication with oil and which bears indicia for enabling an operator to ascertain the oil level, the improvement comprising, in combination, an elongated sleeve for receiving thereinto the elongated measuring rod, a valve for the lower end of the sleeve, means at the upper ends of the rod and sleeve for sealing the sleeve when the rod is positioned to measure the oil level, the rod and sleeve being of selected lengths such that when the rod is positioned to measure the oil level the rod unseats the valve from the lower end of the sleeve, a retainer housing connected to and surrounding the lower portion of the sleeve and the valve, the housing being normally spring biased to urge the valve toward seating position against the sleeve, and aperture means permitting oil to enter past the retainer housing to the interior of the sleeve.

2. In an improved oil level dipstick assembly as described in claim 1, the elongated rod being threaded adjacent its upper end for engagement with a threaded portion of the sleeve.

3. in an improved oil level dipstick assembly as described in claim 1, the elongated rod carrying an encircling ring above the indicia to inhibit contact of the rod with the inner wall of the sleeve.

4. In an improved oil level dipstick as described in claim 1, the sleeve being provided with a bleed aperture intermediate its ends. 

1. In an oil level dipstick assembly that includes an elongated measuring rod the lower portion of which is adapted for communication with oil and which bears indicia for enabling an operator to ascertain the oil level, the improvement comprising, in combination, an elongated sleeve for receiving thereinto the elongated measuring rod, a valve for the lower end of the sleeve, means at the upper ends of the rod and sleeve for sealing the sleeve when the rod is positioned to measure the oil level, the rod and sleeve being of selected lengths such that when the rod is positioned to measure the oil level the rod unseats the valve from the lower end of the sleeve, a retainer housing connected to and surrounding the lower portion of the sleeve and the valve, the housing being normally spring biased to urge the valve toward seating position against the sleeve, and aperture means permitting oil to enter past the retainer housing to the interior of the sleeve.
 2. In an improved oil level dipstick assembly as described in claim 1, the elongated rod being threaded adjacent its upper end for engagement with a threaded portion of the sleeve.
 3. In an improved oil level dipstick assembly as described in claim 1, the elongated rod carrying an encircling ring above the indicia to inhibit contact of the rod with the inner wall of the sleeve.
 4. In an improved oil level dipstick as described in claim 1, the sleeve being provided with a bleed aperture intermediate its ends. 